Production of flax protein isolate

ABSTRACT

Flax and linola oil seed protein isolated are provided. Such isolates are made by extracting flax and linola oil seed protein from the oil seed meal, concentrating the aqueous protein solution, diluting the concentrated protein solution to form protein micelles, collecting mass. Further flax protein isolate may be recovered from the supernatant from the protein micellar formation. The protein isolated have a protein content of at least about 90 wt % (N ×6.25), preferably at least about 100 wt %, on a dry weight basis.

BACKGROUND TO RELATED APPLICATIONS

This application claims priority under 35 USC 119(e) from copending U.S.Patent Applications Ser. Nos. 60/327,775 filed Oct. 10, 2002 and Ser.No. 60/333,492 filed Nov. 28, 2002.

FIELD OF INVENTION

The present invention relates to a novel protein isolate derived fromany flax oil seed, including the low linolenic acid variety linola oilseed, and the production thereof.

BACKGROUND OF THE INVENTION

In U.S. Pat. No. 4,285,862 (Murray IA), there is described the provisionof a protein isolate in the form of an amorphous, viscous, sticky,gluten-like protein mass (PMM), or a dried form of the mass. Theamorphous protein mass is formed settling an aqueous dispersion ofprotein micelles consisting of homogeneous amphiphilic protein moieties.The aqueous dispersion is formed by a procedure described in detail inU.S. Pat. No. 4,208,323 (Murray IB) wherein protein is extracted from aprotein source material using a food grade salt solution undercontrolled conditions, the protein concentration of the resultantextract is increased while maintaining the same salt concentration, andthe concentrated protein solution is diluted, thereby forming theaqueous dispersion of protein micelles. There is no suggestion in thisprior art that the procedures described therein may be applied or may bemodified to apply to the recovery of a flax protein isolate from flaxoil seed meal.

SUMMARY OF INVENTION

The present invention provides a protein isolate of any flax oil seedand a low linolenic acid mutant known as linola oil seed and a procedurefor preparation of the same. A protein isolate is defined as a proteincontaining at least about 90 wt % protein at a Kjeldahl nitrogenconversion rate of N×6.25. The term “protein content” as used hereinrefers to the quantity of protein in the protein isolate expressed on adry weight basis. Such novel protein isolates and their preparation arenot described in the Murray IA and IB patents.

Linola oil seed is a mutant of flax oil seed in which the fatty acidcomposition has been changed and linolenic acid (C18:3) has beensubstantially reduced from about 50% in conventional flax oil seed toabout 2%, through traditional breeding procedures. These modificationswere made to provide from the resulting linola oil seed an ediblepolyunsaturated oil substantially similar to sunflower oil in fatty acidcomposition.

As far as the applicants are aware, there has not previously beendescribed the preparation of protein isolates from flax oil seed orlinola oil seed. The applicants are aware of attempts to provide flaxprotein products, such as described in U.S. Pat. No. 5,925,401, whereina flax product containing 35 to 60 wt % flax protein is provided, wellbelow the protein content required to qualify as an isolate.

Accordingly, in one aspect of the present invention, there is provided aflax oil seed protein isolate having a protein content of at least about90 wt %, as determined by Kjeldahl nitrogen×6.25 (N×6.25) on a dryweight basis, preferably a protein content of at least about 100 wt %.The flax oil seed protein isolate may be derived from linola, a lowlinolenic acid variety of flax oil seed. The flax protein isolatepreferably is provided in a substantially undenatured form. The flaxprotein isolate may be provided in the form of a wet protein micellarmass or in a dry powdered form. The flax protein isolate also may beprovided in the form of dried supernatant from the precipitation of flaxprotein micelles. In addition, the flax protein micelles may be in theform of a dried combination of concentrated supernatant from theprecipitation of flax protein micelles and precipitated flax proteinmicelles.

In another aspect of the present invention, there is provided a processof preparing a flax protein isolate, which comprises (a) extracting aflax oil seed meal to cause solubilization of protein in said oil seedmeal and to form an aqueous protein solution, (b) separating the aqueousprotein solution from the residual oil seed meal, (c) increasing theprotein concentration of said aqueous protein solution while maintainingthe ionic strength substantially constant by using a selective membranetechnique to provide a concentrated protein solution, (d) diluting saidconcentrated protein solution into chilled water to cause the formationof protein micelles, (e) settling the protein micelles to form anamorphous, sticky, gelatinous, gluten-like protein micellar mass, and(f) recovering the micellar mass from supernatant having a proteincontent of at least about 90 wt %, as determined by Kjeldahlnitrogen×6.25 on a dry weight basis.

Supematant from the settling of the protein micellar mass may beprocessed to recover further flax protein isolate. The supernatant maybe concentrated using a membrane technique and the concentratedsupernatant dried. Alternatively, the concentrated supernatant may bemixed with the protein micellar mass and the mixture is dried.

The flax protein isolate product in the form of protein micellar mass isdescribed herein as “gluten-like”. This description is intended toindicate the appearance and feel of the isolate are similar to those ofvital wheat gluten and is not intended to indicate chemical identity togluten.

The flax protein isolate produced according to the process herein may beused in conventional applications of protein isolates, such as, proteinfortification of processed foods, emulsification of oils, body formersin baked goods and foaming agents in products which entrap gases. Inaddition, the protein isolate may be formed into protein fibers, usefulin meat analogs, may be used as an egg white substitute or extender infood products where egg white is used as a binder. The flax proteinisolate may be used as nutritional supplements. Other uses of the flaxprotein isolate are in pet foods, animal feed and in industrial andcosmetic applications and in personal care products.

Flax oil seed also is referred to as linseed oil seed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic flow sheet of a procedure for producing a flax oilseed protein isolate in accordance with one embodiment of the invention.

GENERAL DESCRIPTION OF INVENTION

The novel protein isolates provided herein are prepared by followinggenerally the procedure described in U.S. Pat. No. 4,208,323, preferablyunder the specific conditions described herein. The process may beeffected as a series of batch steps or as a continuous orsemi-continuous process.

The initial step of the process of providing the flax or linola proteinisolates involves solubilizing proteinaceous material from flax orlinola oil seed meal. The proteinaceous material recovered from flax orlinola seed meal may be the protein naturally occurring in flax orlinola seed or the proteinaceous material may be a protein modified bygenetic manipulation but possessing characteristic hydrophobic and polarproperties of the natural protein. The flax or linola meal may be anyflax or linola meal resulting from the removal of flax or linola oilfrom flax or linola oil seed with varying levels of non-denaturedprotein, resulting, for example, from hot hexane extraction or cold oilextrusion methods. The removal of flax or linola oil from flax or linolaoil seed usually is effected as a separate operation from the proteinisolate recovery procedure described herein.

Protein solubilization is effected most efficiently by using a saltsolution since the presence of the salt enhances the removal of solubleprotein from the oil seed meal. The salt usually is sodium chloride,although other salts, such as, potassium chloride, may be used. The saltsolution has an ionic strength of at least about 0.10, preferably atleast about 0.15, generally up to about 2.0 to enable solubilization ofsignificant quantities of protein to be effected. As the ionic strengthof the salt solution increases, the degree of solubilization of proteinin the oil seed meal initially increases until a maximum value isachieved. Any subsequent increase in ionic strength does not increasethe total protein solubilized. The ionic strength of the food grade saltsolution which causes maximum protein solubilization varies depending onthe salt concerned and the oil seed meal chosen.

In view of the greater degree of dilution required for proteinprecipitation with increasing ionic strengths, it is usually preferredto utilize an ionic strength value less than about 1.0 and morepreferably a value of about 0.15 to about 0.6.

In a batch process, the salt solubilization of the protein is effectedat a temperature of above about 0° C. and preferably up to about 35° C.,preferably accompanied by agitation to decrease the solubilization time,which is usually about 10 to about 90 minutes. It is preferred to effectthe solubilization to extract substantially the maximum amount ofprotein from the oil seed meal, so as to improve product yield. Theupper preferred temperature limit of about 35° C. is chosen since theprocess becomes uneconomic at higher temperature levels in a batch mode.

In a continuous process, the extraction of the protein from the flax orlinola oil seed meal is carried out in any manner consistent witheffecting a continuous extraction of protein from the flax or linola oilseed meal. In one embodiment, the flax or linola oil seed meal iscontinuously mixed with a salt solution and the mixture is conveyedthrough a pipe or conduit having a length and at a flow rate for aresidence time sufficient to effect the desired extraction in accordancewith the parameters described herein. In such continuous procedure, thesalt solubilization step is effected rapidly, in a time of up to about10 minutes, preferably to effect solubilization to extract substantiallythe maximum amount of protein from the flax or linola oil seed meal. Thesolubilization in the continuous procedure preferably is effected atelevated temperatures, generally up to about 60° C. or more.

The aqueous food grade salt solution and the flax or linola oil seedmeal have a natural pH of about 5 to about 7 to enable a protein isolateto be formed by the micellar route, as described in more detail below.The optimal pH value for maximum yield of flax or linola protein isolatevaries depending on the flax or linola oil seed meal chosen.

At and close to the limits of the pH range, protein isolate formationoccurs only partly through the micelle route and in lower yields thanattainable elsewhere in the pH range. For these reasons, pH values ofabout 5.3 to about 6.2 are preferred.

The pH of the salt solution may be adjusted to any desired value withinthe range of about 4 to about 7 for use in the extraction step by theuse of any convenient acid, usually hydrochloric acid, or alkali,usually sodium hydroxide, as required.

Another alternative procedure is to extract the oil seed meal with thesalt solution at a relatively high pH value above 7, generally up toabout 12, preferably about 7 to about 9. Greater quantities of proteinare extracted from the oil seed meal at higher pH value. The pH of thesalt solution, may be adjusted in pH to the alkaline value by the use ofany convenient alkali, such as aqueous sodium hydroxide solution. Wheresuch alternative is employed, the aqueous phase resulting from the oilseed meal extraction step then is separated from the residual canolameal, in any convenient manner, such as by employing vacuum filtration,followed by centrifugation and/or filtration to remove residual meal.The separated residual meal may be dried for disposal.

The aqueous protein solution resulting from the high pH extraction stepthen is pH adjusted to the range to about 4 to about 7, preferably about5.3 to about 6.2, as discussed above, prior to further processing asdiscussed below. Such pH adjustment may be effected using any convenientacid, such as hydrochloric acid.

The concentration of oil seed meal in the food grade salt solutionduring the solubilization step may vary widely. Typical concentrationvalues are about 5 to about 15% w/v.

The protein extraction step with the aqueous salt solution has theadditional effect of solubilizing fats which may be present in thecanola meal, which then results in the fats being present in the aqueousphase. It is known that flax or linola oil seed meal containssignificant quantities of a mucilage material which enters the aqueousflax or linola protein solution, tending to make the solution somewhatviscous. Such initial relatively high viscosity tends to inhibit thedegree to which the flax or linola protein solution can subsequently beconcentrated, according to the procedure described below.

The protein solution resulting from the extraction step generally has aprotein concentration of about 5 to about 30 g/L, preferably about 10 toabout 25 g/L.

The aqueous phase resulting from the extraction step then may beseparated from the residual flax or linola oil seed meal, in anyconvenient manner, such as by employing vacuum filtration, followed bycentrifugation and/or filtration to remove residual meal. The separatedresidual meal may be dried for disposal.

Where the flax or linola seed meal contains significant quantities offat, then the defatting steps described in U.S. Pat. Nos. 5,844,086 and6,005,076, assigned to the assignee hereof and the disclosures of whichare incorporated herein by reference may be effected on the separatedaqueous protein solution and on the concentrated aqueous proteinsolution discussed below.

As an alternative to extracting the flax or linola oil seed meal with anaqueous salt solution, such extraction may be made using water alone,although the utilization of water alone tends to extract less proteinfrom the flax or linola oil seed meal than the aqueous salt solution.Where such alternative is employed, then the salt, in the concentrationsdiscussed above, may be added to the protein solution after separationfrom the residual flax or linola oil seed meal in order to maintain theprotein in solution during the concentration step described below.

The aqueous protein solution then is concentrated to increase theprotein concentration thereof while maintaining the ionic strengththereof substantially constant. Such concentration generally is effectedto provide a concentrated protein solution having a proteinconcentration of at least about 50 g/L, preferably at least about 100g/L.

The concentration step may be effected in any convenient mannerconsistent with batch or continuous operation, such as by employing anyconvenient selective membrane technique, such as ultrafiltration ordiafiltration, using membranes, such as hollow-fibre membranes orspiral-wound membranes, with a suitable molecular weight cut-off, suchas about 2000 to about 50,000 daltons, having regard to differingmembrane materials and configurations, and, for continuous operation,dimensioned to permit the desired degree of concentration as the aqueousprotein solution passes through the membranes.

The concentration step may be effected at any convenient temperature,generally about 15° to about 60° C., and for the period of time toeffect the desired degree of concentration. The temperature and otherconditions used to some degree depend upon the membrane equipment usedto effect the concentration and the desired protein concentration of thesolution.

As is well known, ultrafiltration and similar selective membranetechniques permit low molecular weight species to pass therethroughwhile preventing higher molecular weight species from so doing. The lowmolecular weight species include not only the ionic species of the foodgrade salt but also low molecular weight materials extracted from thesource material, such as, carbohydrates, pigments and anti-nutritionalfactors, as well as any low molecular weight forms of the protein. Themolecular weight cut-off of the membrane is usually chosen to ensureretention of a significant proportion of the protein in the solution,while permitting contaminants to pass through having regard to thedifferent membrane materials and configurations.

Depending on the temperature employed in the concentration step, theconcentrated protein solution may be warmed to a temperature of at leastabout 20°, and up to about 60° C., preferably about 25° to about 40° C.,to decrease the viscosity of the concentrated protein solution tofacilitate performance of the subsequent dilution step and micelleformation. The concentrated protein solution should not be heated beyonda temperature above which the temperature of the concentrated proteinsolution does not permit micelle formation on dilution by chilled water.The concentrated protein solution may be subject to a further defattingoperation, if required, as described in U.S. Pat. Nos. 5,844,086 and6,005,076.

The concentrated protein solution resulting from the concentration stepand optional defatting step then is diluted to effect micelle formationby mixing the concentrated protein solution with chilled water havingthe volume required to achieve the degree of dilution desired. Theconcentrated protein solution is diluted by about 15 fold or less,preferably about 10 fold or less.

The chilled water with which the concentrated protein solution is mixedhas a temperature of less than about 15° C., generally about 3° to about15° C., preferably less than about 10° C., since improved yields ofprotein isolate in the form of protein micellar mass are attained withthese colder temperatures at the dilution factors used.

In a batch operation, the batch of concentrated protein solution isadded to a static body of chilled water having the desired volume, asdiscussed above. The dilution of the concentrated protein solution andconsequential decrease in ionic strength causes the formation of acloud-like mass of highly associated protein molecules in the form ofdiscrete protein droplets in micellar form. In the batch procedure, theprotein micelles are allowed to settle in the body of chilled water toform an aggregated, coalesced, dense, amorphous, sticky gluten-likeprotein micellar mass (PMM). The settling may be assisted, such as bycentrifugation. Such induced settling decreases the liquid content ofthe protein micellar mass, thereby decreasing the moisture contentgenerally from about 70% by weight to about 95% by weight to a value ofgenerally about 50% by weight to about 80% by weight of the totalmicellar mass. Decreasing the moisture content of the micellar mass inthis way also decreases the occluded salt content of the micellar mass,and hence the salt content of dried isolate.

Alternatively, the dilution operation may be carried out continuously bycontinuously passing the concentrated protein solution to one inlet of aT-shaped pipe, while the diluting water is fed to the other inlet of theT-shaped pipe, permitting mixing in the pipe. The diluting water is fedinto the T-shaped pipe at a rate sufficient to achieve the desireddegree of dilution.

The mixing of the concentrated protein solution and the diluting waterin the pipe initiates the formation of protein micelles and the mixtureis continuously fed from the outlet from the T-shaped pipe into asettling vessel, from which, when full, supernatant is permitted tooverflow. The mixture preferably is fed into the body of liquid in thesettling vessel in a manner which minimizes turbulence within the bodyof liquid.

In the continuous procedure, the protein micelles are allowed to settlein the settling vessel to form an aggregated, coalesced, dense,amorphous, sticky, gluten-like protein micellar mass (PMM) and theprocedure is continued until a desired quantity of the PMM hasaccumulated in the bottom of the settling vessel, whereupon theaccumulated PMM is removed from the settling vessel.

By the utilization of a continuous process for the recovery of flax orlinola protein isolate as compared to the batch process, the initialprotein extraction step can be significantly reduced in time for thesame level of protein extraction and significantly higher temperaturescan be employed in the extraction step. In addition, in a continuousoperation, there is less chance of contamination than in a batchprocedure, leading to higher product quality and the process can becarried out in more compact equipment.

The settled isolate is separated from the residual aqueous phase orsupernatant, such as by decantation of the residual aqueous phase fromthe settled mass or by centrifugation. The PMM may be used in the wetform or may be dried, by any convenient technique, such as spray drying,freeze drying or vacuum drum drying, to a dry form. The dry flax orlinola protein isolate has a high protein content, in excess of about 90wt % protein, preferably at least about 100 wt % protein (calculated asKjeldahl N×6.25), and is substantially undenatured (as determined bydifferential scanning calorimetry). The dry flax protein isolateisolated from fatty oil seed meal also has a low residual fat content,when the procedures of U.S. Pat. Nos. 5,844,086 and 6,005,076 areemployed, which may be below about 1 wt %.

In accordance with one aspect of the invention, it has now been foundthat the supernatant from the PMM formation and settling step containssignificant amounts of flax or linola protein, not precipitated in thedilution step.

In such procedure, the supernatant from the dilution step, followingremoval of the PMM, may be concentrated to increase the proteinconcentration thereof. Such concentration is effected using anyconvenient selective membrane technique, such as ultrafiltration, usingmembranes with a suitable molecular weight cut-off permitting lowmolecular weight species, including the food grade salt and othernon-proteinaceous low molecular weight materials extracted from thesource material, to pass through the membrane, while retaining flaxprotein in the solution. Ultrafiltration membranes having a molecularweight cut-off of about 3000 to 10,000 daltons having regard todiffering membranes and configurations, may be used. Concentration ofthe supernatant in this way also reduces the volume of liquid requiredto be dried to recover the protein, and hence the energy required fordrying. The supernatant generally is concentrated to a protein contentof about 100 to 400 g/L, preferably about 200 to about 300 g/L, prior todrying.

The concentrated supernatant may be dried by any convenient technique,such as spray drying, freeze drying or vacuum drum drying, to a dry formto provide a further flax protein isolate. Such further flax proteinisolate has a high protein content, usually in excess of about 90 wt %protein (calculated as Kjeldahl N×6.25) and is substantially undenatured(as determined by differential scanning calorimetry). If desired, thewet PMM may be combined with the concentrated supernatant prior todrying the combined protein streams by any convenient technique toprovide a combined flax protein isolate. The combined flax proteinisolate has a high protein content, in excess of about 90 wt %(calculated as Kjeldahl N×6.25) and is substantially undenatured (asdetermined by differential scanning calorimetry).

In another alternative procedure, a portion only of the concentratedsupernatant may be mixed with at least part of the PMM and the resultingmixture dried. The remainder of the concentrated supernatant may bedried as any of the remainder of the PMM. Further, dried PMM and driedsupernatant also may be dry mixed in any desired relative proportions.

By operating in this manner, a number of flax protein isolates may berecovered, in the form of dried PMM, dried supernatant and driedmixtures of various proportions by weight of PMM and supernatant,generally from about 5:95 to about 95:5 by weight, which may bedesirable for attaining differing functional and nutritional properties.

As an alternative to dilution of the concentrated protein solution intochilled water and processing of the resulting precipitate andsupernatant as described above, protein may be recovered from theconcentrated protein solution by dialyzing the concentrated proteinsolution to reduce the salt content thereof. The reduction of the saltcontent of the concentrated protein solution results in the formation ofprotein micelles in the dialysis tubing. Following dialysis, the proteinmicelles may be permitted to settle, collected and dried, as discussedabove. The supernatant from the protein micelle settling step may beprocessed, as discussed above, to recover further protein therefrom.Alternatively, the contents of the dialysis tubing may be directlydried. The latter alternative procedure is useful where small laboratoryscale quantities of protein are desired.

An alternative procedure for production of the flax protein isolate isto utilize an iso-electric precipitation procedure. In such a procedure,extraction of the oil seed meal is effected under alkaline conditions,following which the pH of the protein solution is adjusted to a lowervalue, particularly the pH of the iso-electric point of the targetedprotein, at which pH value the protein has a neutral change andprecipitates out of solution. The precipitates may be washed to removecontaminants by resuspending the precipitate in water andreprecipitating the protein.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIG. 1, there is illustrated schematically a flow sheet ofa batch process carried out in accordance with one embodiment to theinvention. Flax oil seed meal, which may be linola oil seed meal, andaqueous extraction medium are fed by line 10 to an extraction vessel 12wherein the oil seed meal is extracted and an aqueous protein solutionis formed. The slurry of aqueous protein solution and residual oil seedmeal is passed by line 14 to a vacuum filter belt 16 for separation ofthe residual oil seed meal which is removed by line 18. The aqueousprotein solution then is passed by line 20 to a clarification operation22 wherein the aqueous protein solution is centrifuged and filtered toremove fines, which are recovered by line 24.

The clarified aqueous protein solution is pumped by line 26 throughultrafiltration membrane 28 to produce a concentrated protein solutionas the retentate in line 30 with the permeate being recovered by line32. The concentrated protein solution is passed into a precipitationvessel 34 containing cold water fed by line 36. Protein micellar massformed in the precipitation vessel 34 is removed by line 38 and passedthrough a spray dryer 40 to provide dry flax protein isolate 42.

Supernatant from the precipitation vessel 34 is removed by line 44 andpumped through ultrafiltration membranes 46 to produce a concentratedprotein solution as the retentate in line 48 with the permeate beingremoved by line 50. The concentrated protein solution is passed througha spray dryer 52 to provide further dry flax protein isolate 54.

As an alternative, the concentrated protein solution in line 48 may bepassed by line 56 to mix with the protein micellar mass before themixture then is dried in spray dryer 40.

EXAMPLES Example 1

This Example illustrates the recovery of linola protein from linola oilseed.

Linola oil seed was cold pressed and the oil recovered. 16.8 kg ofcrushed meal was added to 335 L of 0.15 M NaCl solution (5% w/vextraction concentration at 13° C.) and the mixture agitated for 60mins, followed by a 60 min. settling period. 190 L of extract wasdecanted and filtered through 20 μm filter pads to provide 180 L of anaqueous protein solution having a protein content of 6 g/L.

The aqueous solution was reduced in volume to 11 L by concentration onan ultrafiltration system using 30,000 daltons molecular weight cut-off.The resulting concentrated solution had a protein content of 6 g/L,which represented a yield of 51 wt % of the protein originally extractedfrom the linola meal.

The concentrated protein solution at a temperature of 30° C. was addedto water at 4° C. at a dilution ratio of 1:10. A white cloud formedimmediately and was allowed to settle for 16 hours. 93 L of supernatantwas decanted leaving 12 L of precipitated, viscous, sticky protein mass(PMM). An aliquot of PMM was freeze dried to determine protein content.The freeze dried PMM was found to have a protein content of 92 wt % (N×6.25) d.b. The overall yield of protein from the protein extracted fromthe linola meal was 27 wt %.

Example 2

This Example illustrates the recovery of flax protein from flax oil seedmeal.

17.5 kg of commercial flax oil seed meal was added to 350 L of 0.5M NaClsolution (5% w/v) at 20° C. and the mixture was agitated for 60 minutesfollowed by 60 minutes settling time. The resulting protein extractsolution had a protein concentration of 8.5 g/L. A further 17.5 kg batchof commercial flax oil seed meal was processed in the same way and theresulting protein extract solution had a protein concentration of 7.9g/L. The two extract solutions were decanted and filtered using 20 μmfilter pads in a filter press and the filtrates combined.

The filtered aqueous protein solution then was concentrated on anultrafiltration system using 5,000 daltons molecular weight cut-off toprovide 11 L of a concentrated aqueous protein solution having a proteincontent of 120 g/L.

The concentrated protein solution at a temperature 31° C. was added totap water at 4° C. at a dilution ratio of 1:10. A white cloud formedimmediately and was allowed to settle for 16 hours at 4° C. 105 L ofsupernatant was decanted leaving 10 L of precipitated, viscous, stickyprotein mass (PMM). The PMM was centrifuged at 10,000 g for five minutesto provide a dense white mass, which then was freeze dried.

178 g of dried protein isolate was recovered, corresponding to anoverall yield of protein extracted from the flax oil seed meal of 6 wt%. The freeze dried PMM was found to have a protein content of 109 wt %(N ×6.25) d.b.

Example 3

This Example illustrates the effect of pH on linola extraction.

Linola oil seed meal was extracted in a 5% w/v solution with theextraction pH adjusted with either NaOH or HCl to the derived pH levelsof 4, 5, 6, 7, 8, 9, 10, 11 and 12. All extractions were performed atroom temperature and effected in an orbital shaker for 30 minutes at 230RPM. Following the mixing period, the spent meal was separated from theextract and samples taken for protein content analysis.

The results obtained are set forth in the following Table I:

TABLE I Extraction pH Extraction Protein 12 0.942% 11 0.708% 10 0.522% 90.616% 8 0.514% 7 0.330% 6 0.264% 5 0.165% 4 0.188%

As may be seen, the extractions are higher pH yielded more protein thanthe lower pH extractions. Extractions at pH 5.0 and 4.0 were quitecloudy in appearance, indicating some precipitation.

SUMMARY OF DISCLOSURE

In summary of this disclosure, the present invention provides novel flaxand linola protein isolates and procedures for their preparation.Modifications are possible within the scope of the invention.

1. A process of preparing a flax protein isolate, which comprises: (a)extracting a flax oil seed meal to cause solubilization of protein insaid oil seed meal and to form an aqueous protein solution, (b)separating the aqueous protein solution from the residual oil seed meal,(c) increasing the protein concentration of said aqueous proteinsolution while maintaining the ionic strength substantially constant byusing a selective membrane technique to provide a concentrated proteinsolution, (d) said concentrated protein solution is warmed to atemperature of at least about 20° C. to decrease the viscosity of theconcentrated protein solution but not beyond a temperature above whichthe temperature of the concentrated protein solution does not permitmicelle formation upon subsequent dilution, (e) diluting saidconcentrated protein solution into chilled water to cause the formationof protein micelles, (f) settling the protein micelles to form anamorphous, sticky, gelatinous, gluten-like protein micellar mass, and(g) recovering the micellar mass from supernatant having a proteincontent of at least about 90 wt %, as determined by Kjeldahl nitrogen×6.25 on a dry weight basis.
 2. The process of claim 1 wherein saidextracting of said flax oil seed meal is effected using an aqueous saltsolution having an ionic strength of at least about 0.10 and a pH ofabout 4 to about
 7. 3. The process of claim 2 wherein said salt solutionhas an ionic strength of about 0.15 to about 0.6.
 4. The process ofclaim 2 wherein said salt solution has a pH of about 5.3 to about 6.2.5. The process of claim 1 wherein said extracting of said flax oil seedmeal is effected using an aqueous salt solution having an ionic strengthof at least about 0.10 and a pH of about 7 to about
 12. 6. The processof claim 5 wherein said pH is about 7 to about
 9. 7. The process ofclaim 5 wherein, following said extraction step, the pH of the aqueousprotein solution is adjusted to about 4 to about 7 prior to saidconcentration step.
 8. The process of claim 1 wherein said oil seed mealis extracted by water and subsequent thereto salt is added to theresulting aqueous protein solution to provide an aqueous proteinsolution having an ionic strength of at least about 0.10.
 9. The processof claim 1 wherein said aqueous protein solution has a protein contentof about 5 to about 30 g/L.
 10. The process of claim 1 wherein saidprotein concentrating step is effected to provide a concentrated proteinsolution having a concentration of at least about 50 g/L.
 11. Theprocess of claim 10 wherein the protein concentration is at least about100 g/L.
 12. The process of claim 1 wherein said concentrated proteinsolution is diluted by about 15 fold or less by adding the concentratedprotein solution into a body of water having the volume required toachieve the desired degree of dilution.
 13. The process of claim 12wherein said body of water has a temperature of less than about 10° C.14. The process of claim 13 wherein said concentrated protein solutionis diluted by about 10 fold or less.
 15. The process of claim 1 whereinthe recovered protein micellar mass is dried to a proteinaceous powder.16. The process of claim 1 wherein supernatant from the settling step isprocessed to recover further flax protein isolate.
 17. The process ofclaim 16 wherein the supernatant is concentrated using a membranetechnique and the concentrated supernatant is dried.
 18. The process ofclaim 1 wherein steps (a) to (g) are effected in batch operation. 19.The process of claim 1 wherein steps (a) to (g) are effected in acontinuous operation.
 20. The process of claim 1 wherein steps (a) to(g) are effected in a semi-continuous manner.
 21. The process of claim 1wherein said flax oil seed meal is linola oil seed meal.